How to Fix / Troubleshooting

Safety: Isolate electrical supply before touching the pump or removing covers. Surfaces may be hot.

User checks:

Bleed radiators and ensure system pressure is correct (1.0–1.5 bar).
Listen near the boiler when there is a demand: if you hear humming but no water movement, the pump may be stuck.

Engineer checks:

Remove the pump head cover on the Keston circulation pump and attempt to turn the shaft with a screwdriver to free a stuck rotor.
Check for 230 V supply at the pump terminals when the boiler is calling for heat; if no voltage, suspect PCB or wiring.
Measure pump winding resistance and test the start capacitor if fitted; replace the pump head or complete pump assembly if defective.
Ensure all isolation valves around the pump are open and that there are no blockages in the nearby pipework or strainers.

Boiler shows E09, no heating or hot water, pump may run briefly

Possible Causes